1. Field of the Invention
The present invention relates to a substrate processing apparatus that subjects a substrate to processing.
2. Description of the Background Art
Substrate processing apparatuses have been conventionally used to perform various types of processings on substrates such as semiconductor wafers, glass substrates for photomasks, glass substrates for liquid crystal displays, glass substrates for optical disks or the like.
For example, a substrate processing apparatus that performs a cleaning processing on a back surface of a substrate is provided with a substrate reversing device for reversing the top surface and the back surface of the substrate. For example, the substrate processing apparatus including the substrate reversing device is described in JP 2006-12880 A.
Such a substrate processing apparatus reverses the substrate by the substrate reversing device before performing the cleaning processing on the back surface of the substrate so that the back surface thereof is directed upward. After the cleaning processing is performed on the back surface of the substrate, the substrate is reversed again by the substrate reversing device so that the top surface thereof is directed upward.
Normally, a transport robot carries the substrate into and out of the substrate reversing device. Two hands for holding the substrate are provided so as to vertically overlap with each other in the transport robot. For example, in a case where the transport robot carries the substrate after reversing out of the substrate reversing device by an upper hand with a lower hand holding the substrate before the reversing, and subsequently carries the substrate before the reversing into the substrate reversing device by the lower hand, the following operation is performed. First, the upper hand advances into the substrate reversing device while being positioned at the level of the substrate reversing device, holds the substrate after the reversing and withdraws. Then, after the upper and lower hands are lifted so that the lower hand is positioned at the level of the substrate reversing device, the lower hand advances into the substrate reversing device and places the substrate before the reversing in the substrate reversing device.
As described above, the upper and lower hands are required to be vertically moved in order that the substrate after the reversing is carried out of the substrate reversing device by the one hand and the substrate before the reversing is subsequently carried into the substrate reversing device. Thus, it takes a fixed amount of time to carry the substrate into and out of the substrate reversing device. This prevents the throughput in the substrate processing apparatus from being improved.